D

Data model

The way persistent state is stored in the datastore. For a relational database, this would be the relational model.

Data object

An instance of a persistence-capable class.

Datastore

Any service that can store state information and provide a means to query, read, update, insert, and delete it. JDO requires a datastore that supports transactions.

Datastore object

Shorthand for the persistent state of an object in the datastore.

Datastore transaction

A JDO transaction that relies on the transactional boundaries of the underlying datastore service.

Default fetch group

A subset of the persistent fields of an application data class. The JDO metadata defines either explicitly or by default which persistent fields are members of the default fetch group. As an optimization, the JDO implementation may load all the fields of the default fetch group at the same time.

Dirty

When the persistent field of a managed object is changed, the field and the object are said to be dirty.